1. Field of the Invention
The present invention generally relates to dual wall accordion folding doors and, more particularly, a hinge strip of one-piece construction pivotally connecting the edges of the four panels thereby forming the hinge axis or axes and forming a seal for maintaining the acoustical as well as the other properties of the door.
2. Description of the Prior Art
Acoustical folding doors, including dual wall accordion folding doors, are known in the art. For example, in our prior U.S. Pat. No. 3,348,628, issued Oct. 24, 1967, an acoustical folding door of this type is disclosed. However, the structures which defined the interior hinges for the dual walls of the door used in previous devices of this type utilize a rigid hinge strap to define the hinge axes for the four edges of the panels defining the interior hinge connection of the dual walls with the rigid hinge strap also, in some instances, being used to engage the supporting roller assembly suspended from the overhead track thereby supporting the door. Such hinge arrangements, being of rigid materials, transmit sound vibrations from one wall of the door to the other and also transmit sound vibrations between the door and the overhead track. Also, while the hinge structure disclosed in the aforementioned patent operates effectively, the rigidity and weight of the hardware results in a relatively bulky and high cost construction which, in some installation, are not permissible.